Commonly, in interior building construction, a drywall panel is erected so that its top or side edge is near an exposed surface of an adjacent structure, such as an acoustic tile ceiling, a masonry wall, or a window frame. It is common to leave a small gap between the panel edge and the exposed surface to accommodate a bead of a type having a generally L-shaped profile defining two legs joined by a generally U-shaped lip. One such leg is engaged with an outer surface of the drywall panel and is secured to the drywall panel, as by staples or nails, so that the other leg extends inwardly and covers at least part of the panel edge. A bead of the type noted above, extruded from rigid poly(vinyl chloride) known commonly as rigid PVC, has been sold for many years by Trim-Tex Inc. of Lincolnwood, Ill., under the trade designation "L Bead". Such a bead may be also called a trim bead, an edge bead, or a finishing bead.
Drywall finishing material of a type commonly known as joint compound, masking compound, or drywall "mud" is spread onto the leg secured to the drywall panel, and onto an adjacent portion of the outer surface of the drywall panel, usually by means of a wide trowel guided by the lip and by the panel surface. After such material has dried sufficiently, adjacent portions of the outer surface of the drywall panel, the exposed surface of the finishing material, and any exposed surface of the lip of the bead may be then painted or wallpapered.
Another trim or finishing bead known heretofore has a tear-away strip extending outwardly from the lip. The tear-away strip is used to mask a portion of an adjacent surface so as to prevent drywall finishing material from engaging the masked portion. The tear-away strip can be torn away, along a weakened line, when such strip is no longer needed. Another known bead for similar uses has a paper masking strip attached adhesively to the edge-covering leg so as to extend outwardly from the lip. The paper masking strip can be cut away from the finishing bead.
Van Bael U.S. Pat. No. 3,290,838 discloses a casement bead having a plastering splash apron, which comprises a strip of flexible material attached to the casement bead. The strip has a line of perforations spaced inwardly from a corner of the casement bead. When a lower portion of the strip is broken away, along the line of perforations, an upper portion of the strip remains hidden within a narrow gap between the casement bead and an adjacent surface.
Rutherford U.S. Pat. No. 4,074,478 discloses a casing bead of related interest, apparently made of thin sheet metal, with a tear strip that can be torn away along a scored line directly opposite the lip. Uttley et al. U.S. Pat. No. 4,587,781 and Thompson U.S. Pat. No. 4,982,540 disclose drywall trim pieces of related interest, generally T-shaped in cross-section, without tear-away strips. Taravella U.S. Pat. No. 4,843,783 discloses a casing trim of related interest, with an inwardly opening channel receiving a flat vinyl strip.